Internal combustion engine



April 12, 1932. s. WALKER 3,853,290

INTERNAL COMBUSTION ENGINE Filed Sept. 22, 1928 3 Sheets-Sheet l TTORNEYS.

I N V EN TOR.

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INTERNAL COMBUSTION ENGINE Filed Sept. 22, 1928 s Sheets-Sheet 2 N 3 INVENTOR. W W

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Filed Sept. 22 1928 o miidja Patented Apr. 12, 1932 UNITED STATES PATENT OFFICE,

- IBJROOKS' WALKER, OF PIEMONT, CALIFORNIA, ASSIGNOR OF ONE-THIRD T CLINTON L. WALKER, OE PIEDMONT, CALIFORNIA, AND

OF BERKELEY, (IAIJEE'OREF-EA,

ONE-THIRD TO HARRY E. KENNEDY,

INTERNAL coinnnsrron" anemia Application filed September e2, 1928. Serial no. 307,588.

al to compression pressure within the range of operation. Hence, if a uniform peak compression pressure can be maintained under all throttle conditlons, a materlal increase .in fuel economy will result particularly at the lower throttle conditions.

As the peak compression pressure varies in the conventional engine in substantially direct ratio ,to the amount of mixture taken into the cylinder, the mean effective pressure on the piston will accordingly vary. This varying. pressure may be employed as a medium to actuate a mechanism whereby a uniform peak compression pressure may be malntained.

Therefore, it is the principal object of the present invention to provide an engine in which the variations in mean efi'ective pres sure is utilized to automatically increase or, decrease the size or capacity of the compression chamber, so as to maintain a uniform peak compression pressure during all operating conditions. The invention is illustrated by way of example in'the accompanyin% drawings, in which: I 1

ig. 1 is a central vertical cross section of the engine illustrated in Figs. 2 and 3,

Fig. 2 is a plan view of the engine,-

Fig. 3 is a slde elevation,

Fig. 4 is an enlarged detailed view of the dashpot'mechanism showing a modified con struction thereof,

Fig. 5 is a partial side elevation of a radial. type of motor showing the application of the invention,

Fig. 6 is an enlarged cross-section taken on line V-V of Fig. 5, V v

Fig. 7 is an enlarged fragmentary view in section through the means which form a connection between the crank shaft and the shaft which controls the operation of the eccentric bushing. 7

Referring to the drawings in detail, particularly Fig 1, A indicates the cylinder block, B the head, C the piston, D the connecting rod, E the crank shaft and. F thecrank case. A standard form of crank shaft is employed and it is journalled in the crank case in the usual manner. A standard form of connecting rod and piston is also employed, and they operate, in the usual manner. The engine is otherwise provided with an inlet valve 2, an exhaust valve 3 and an overhead cam shaft 4: whereby the valves are actuated. In the present instance, it is desired to maintain a uniform peak compression pressure under all throttle openings, and it is accordingly necessary to increase or decrease the clearance volume or the capacity of the compression space between the piston and the head under varying throttle openings. To accomplish this, the cylinder block together with the head, cam shaft, valves etc., are mounted to move vertically with relation to the crank shaft and the pistons. The

lower ends of the cylinders are accordingly .slidably mounted with relation to the upper end ofthe crank case, as indicated at 5, and flexible sealing tubes 6 surround the lower ends of the cylinders so as to prevent oil leakage. y

In view of. the fact that the cylinders are vertically movable with relation to the crank shaft and pistons to increase or decrease the clearance volume, means must be provided for limiting, both the upward and the downward movement of the same. This is accomplished as follows:

By referring to Figs. 2 and 3, it will be noted that the cylinder head B is provided with a number of bearings, as indicated at 7 and that a crank shaft 8 is journalled therein. The shaft is provided with crank webs 9 at opposite ends and also with crank pins 10. These are journalled as at 11 in the up- 1 per ends of connecting rods 12, and the lower ends of the rods are pivotally secured as at 14 to opposite ends of the crank shaft case. An operating arm 15 is secured to the crank shaft 8 approximately centrally thereof, and this is connected through a rod 16 with a piston 17which operates in the cylinder 18 of a dash pot, the lower end of this cylinder be- V the head as on the pistons,

clearance volume between ing pivotally secured as at 19 to a bracket 20 speed of the movement is determined by the pressure applied and by the size of the ports 21, or piston clearance. A tension spring 22 surrounds the cylinder 18, and is secured to the lower end thereof as at 23, the upper end of the spring being secured. to a collar 24, which in turn is secured to the piston rod 16.

To understand the operation of the engine, it is first necessary to point out the fact that the mean effective pressure in the combustion chamber is in substantially direct ratio to the amount of mixture taken into the cylinder. The mean eiiective pressure is, of course, exerted just as much vertically on and as the head is tied to the cylinders, it is obvious that if the cylinders were free to move upwardly in a vertical direction that the cylinder would raise. This is, in fact, the actual thing that takes place, as the mean effectve pressure increases, the clearance volume between the head and the piston increases as the cylinders and the head raise, and as the mean effective pressure decreases, the cylinders and the head lower themselves, both by gravity action due to the weight of the cylinders and the head, and due to the pull of the spring 22. By this movement of the cylinders and the head with relation to the piston, it is possible to vary the clearance v'olume between the pistons and the head and the result it a uniform peak compression pressure regardless of throttle opening.

When the crank shaft 8 assumes its uppermost position shown in Figs. 1 and 3, the the head and the pistons is the greatest and this position is assumed when the maximum mean efiective pressure is being developed. The upward movement of the cylinders and head in this instance is limited by the position of the crank pins 10, which is determined by the spring tension and the length of the dash pot cylinder, and the connecting rods 12. On the other hand, as the throttle closes, the mean efi'ec tive pressure drops and the; cylinders and head instantly move downwardly with relation to the pistons. This downward movement is effected by the weight of the cylinders and head and the valves and cam, etc. carried thereby, and also by the pull of the spring 23. The downward movement however, is limited by the length of'the dash pot stroke, the movement of the cylinders and head, either upwardly or downwardly being in all instances cushioned and smooth, due to the dash pot action obtained by the piston 17 and the cylinder 18.

The cylinders are guided with relation to the crank casing first at their lower ends, as shown at 5 in Fig. 1, and secondly by a pair of guide ribs 30, formed on opposite ends of the cylinder block, which engage guideways 81 carried by the crank case. The engine shown illustrates an overhead cam shaft, and where such construction is employed the, vertical drive shaft shown at 33 is splined at its upper end, as indicated at 34, so as to permit a continuous drive through the bevel gears 35 as the cylinders and head change their position vertically. In Figs. 1, 2 and 3 the pistons C function as an abutment as the cylinders and head are raised and lowered with relation thereto, to change the clearance volume.

In Figs. 4 and 5 a modified form of the invention is illustrated as it is shown applied to a radial type of aviation motor. In this instance, the cylinders 40 are rigidly secured to the crank case 41, so that no movement of the cylinders can take place. With such a structure it is necessary to increase or decrease the relative piston stroke to change the clearance volume and that is accomplished in the present instance by placing an eccentric 42 on the crank pin 43 of the crank shaft. The master connecting rod 44 is journalled on the eccentric; the eccentric is in turn journalled on the crank pin 43. It is provided with a crank arm 45 at one end, and it is connected through means of a link 46 with a second crank arm 47 which is secured to a shaft 48, which extends through the crank shaft proper. A sleeve 49, actuated by a forked lever 50 is splined and slidably mounted on the outer end of the crank shaft. It is provided with a cam slot 51, which actuates a pin 52 secured to the shaft 48. The forked lever 50 is connected with a compression spring and this tends to hold the sleeve 49 in the position shown in Fig. 5. That is, in a position where it will maintain eccentric 42 in its highest position, this position being assumed when the engine is operating under minimum load or mean effective pressure, or substantially closed throttle. As the throttle opens and 'mean effective pressure increases the force is exerted on the eccentric 42 and it is partially rotated; This rotary movement is transmitted through the crank arms 42 and 47 and link 46, to rotate shaft 48 and as this is rotated pin 52 causes longitudinal movement of the sleeve 49, thereby imparting rocking movement to the forked lever 50, which places the spring 53 under greater compression.

The pin 52 reaches the opposite end of the slot 51 when the throttle is fully opened, or when maximum mean effective pressure is exerted. The clearance volume will, of course, then be at maximum but the compression pressure will remain constant during all throttle conditions,

as the pressure of the spring 53 will reverse the movement of the Y ly no resistance.

fective pressure decreases.

\ eccentric 42 as the mean effective pressure starter rotates the crank shaft and recipro-- cal movement is imparted to the pistons it' is obvious that the clearance space is so small that unless a powerful starter is employed, it would be difilcult to turn the crank shaft over against the high compression which would be encountered until the intake pressure is substantially lowered. To avoid this difiiculty a latch, such as indicated at 60, see

Fig. 4 is employed. This latch is mounted in the collar 24, and it normally engages a recess 61 in the piston rod 16, thereby locking the collar to the rod. This latch is held in locked position by means of a spring 62 but it may be retracted by means of a pull wire 63, which is'attached to a foot pedal 64. This pedal is placed directly above the starter button 65, hence when it is desired to start the motor, it is only necessary to depress the foot pedal 64 in unison with the starter button. Such depression of the foot pedal releases the latch and spring 22 is thus released, so that the cylinders and head may raise with relation to the pistons without placing the spring under tension. Hence, as the crank shaft starts to turn and the pistons move up wardly, high compression is avoided as the cylinders are free to raise with comparative- The moment, however, the engine starts running under idling conditions, the mean effective pressure becomes so low that the cylinders and head will settle to their lowermost position due to their weight.

At this point ,the recesses 61 in the piston rod 16 will register with the latch and automatic engagement is then made as the latch is spring actuated. Thereafter as the throttle is opened, spring tension or pull is appliedand the motor will function against the tension of the spring 22.

'In some instances it is possible that the frictional resistance of the cylinders, with relation to the pistons, the guides, etc. may be 'so great that the weight alone is not suflicient to lower the cylinders to their lowermost position. In such cases, an auxiliary spring may be employed, this spring having just sufiicient tension to overcome the frictional resistance of the cylinders, thereby insuring lowering of the cylinders when the mean ef- The mean efi'ective pressure within the cylinder will vary with changes in atmospheric pressure or changes in volumetric efiiciency usually encountered at higher engine speeds. As the mean effective pressure controls the clearance Volume a substantially uniform peak compression pressure will be maintained throughout these different operating conditions.

While certain features ,ofthe present invention are more or less specifically described,- I wish it understood that various changes may be resorted to within the scope of the appended claims, similarly that the materials and finishes of the several parts employed may be such as the manufacturer may decide, or varying conditions or uses may demand.

c Having thusdescribed my invention, what 1 claim and desire-to secure by Letters Patent 1S 1. in an engine of the character described a crank shaft casing, a crank shaft j ournalled therein, a connecting rod, a piston, a cylinder in which the piston is reciprocally mounted,

means permitting movement of the cylinder with relation to the piston and the crank shaftcasing, a head on the cylinder, movable with the cylinder, and means for automatically maintaining the cylinder and the head in a pre-determined position where the clearance volume between the piston and the head will be at a minimum when the engine is idling, said means permitting axial movement of the cylinder and head, with relation to the piston and crank shaft casing, as mean ef-v fective pressure within the cylinder increases,

so as to maintain a substantially uniform peak compression pressure during all operating conditions.

2. In an engine of the character described, a movable cylinder unit, a crank shaft and piston having a fixed stroke, and means ac.- tuated by changes of mean effective pressure within the cylinders for imparting movement to the cylinder unit, so as to automatically maintain a substantiallyuniform peak compression pressure during the changes of mean effective pressure.

3. An engine of the character described comprising a multiplicity of cylinders relaa crank shaft common to the pistons, said cyliii; 'tively fixed together, pistons in the cylinders,

inders being movable relative to the crank shaft, operative means associated with the cylinders and controlled by the mean effective pressure in the combustion chambers of the cylinders and capable upon changes in the mean effective pressure for varyin the clearance volume in the cylinders in su s'tantially direct ratio to the changes in the mean effective pressure and thereby maintain a substantially uniform peak compression pressure during all the operating conditions, said means being effected by variations in the mean effective pressure only whereby the 4- aeeaeeo clearance volume will remain substantially constant during all cycles of like mean effective pressure.

4. An engine of the character described comprising a cylinder, a. piston reciprocably mounted therein, a crank shaft having a crank connected with the piston, said cylinder and crank shaft being relatively movable in a direction at right angles to the axis of the crank shaft, operative means controlled by the mean effective pressure in the combustion chamber of the cylinder and capable upon changes in the mean effective pressure of creating a relative movement between the cylinder and crank shaft to vary the clearance volume in the cylinder in substantially direct ratio to the changes in the mean efliective pressure and thereby maintain a substantially uniform peak compression pressure during operation of the engine, said means being affected by variations in the mean effective pressure only whereby the clearance volume will remain substantially constant during all cycles of like mean eflective pressure.

5. An engine of the character described comprising a cylinder, a piston reciprocably mounted therein, a crank shaft having a crank connected with the piston, said cylinder and crank shaft being relatively movable in a direction at right angles to the axis of the crank shaft, operative means controlled by the mean eiiective pressure in the combustion chamber of the cylinder and capable upon changes in the mean efiective pressure 3 of creating a relative movement between the cylinder and crank shaft to vary the clearance volume in the cylinder when variations occur in the mean effective pressure, said means being afiected by variations in mean 1 effective pressure only whereby the clearance volume will remain substantially constant during all cycles of like mean eifective pressure.

BROOKS WALKER. 

